Every year, thousands of people travel to high-altitude environments for tourism, adventure-seeking, or to train and compete in various sports. Unfortunately, these trips can be marred by the effects of acute altitude sickness, and the symptoms vary from person to person. To understand why people are affected differently, we have to look at how the body is affected by altitude.
Air is comprised of different molecules, with nitrogen (79.04%) and oxygen (20.93%) making up the majority of each breath we take. This composition of air remains consistent, whether we are at sea level or at altitude.
However, with altitude, the “partial pressure” of oxygen in this air (how many molecules of oxygen are in a given volume of air) changes. At sea-level, the partial pressure of oxygen is 159 mmHg, whereas at 8,848m above sea level (the summit of Mt Everest), the partial pressure of oxygen is only 53 mmHg.
At high altitudes, oxygen molecules are further apart because there is less pressure to “push” them together. This effectively means there are fewer oxygen molecules in the same volume of air as we inhale. In scientific studies, this is often referred to as “hypoxia”.
What happens in the body in high altitudes?
Within seconds of exposure to altitude, ventilation is increased, meaning we start trying to breathe more, as the body responds to less oxygen in each breath, and attempts to increase oxygen uptake. Despite this response, there’s still less oxygen throughout your circulatory system, meaning less oxygen reaches your muscles. This will obviously limit exercise performance.
Within the first few hours of altitude exposure, water loss also increases, which can result in dehydration. Altitude can also increase your metabolism while suppressing your appetite, meaning you’ll have to eat more than you feel like to maintain a neutral energy balance.
When people are exposed to altitude for several days or weeks, their bodies begin to adjust (called “acclimation”) to the low-oxygen environment. The increase in breathing that was initiated in the first few seconds of altitude exposure remains, and haemoglobin levels (the protein in our blood that carries oxygen) increase, along with the ratio of blood vessels to muscle mass.
Despite these adaptations in the body to compensate for hypoxic conditions, physical performance will always be worse at altitude than for the equivalent activity at sea level. The only exception to this is in very brief and powerful activities such as throwing or hitting a ball, which could be aided by the lack of air resistance.
Many people who ascend to moderate or high altitudes experience the effects of acute altitude sickness. Symptoms of this sickness typically begin 6-48 hours after the altitude exposure begins, and include headache, nausea, lethargy, dizziness and disturbed sleep.
These symptoms are more prevalent in people who ascend quickly to altitudes of above 2,500m, which is why many hikers are advised to climb slowly, particularly if they’ve not been to altitude before.
It’s difficult to predict who will be adversely affected by altitude exposure. Even in elite athletes, high levels of fitness are not protective for altitude sickness.
There’s some evidence those who experience the worst symptoms have a low ventilatory response to hypoxia. So just as some people aren’t great singers or footballers, some people’s bodies are just less able to cope with the reduction in oxygen in their systems.
There are also disorders that impact on the blood’s oxygen carrying capacity, such as thalassemia, which can increase the risk of symptoms.
But the best predictor of who may suffer from altitude sickness is a history of symptoms when being exposed to altitude previously.
How are high-altitude natives different?
People who reside at altitude are known to have greater capacity for physical work at altitude. For example, the Sherpas who reside in the mountainous regions of Nepal are renowned for their mountaineering prowess.
High-altitude natives exhibit large lung volumes and greater efficiency of oxygen transport to tissues, both at rest and during exercise.
While there is debate over whether these characteristics are genetic, or the result of altitude exposure throughout life, they provide high-altitude natives with a distinct advantage over lowlanders during activities in hypoxia.
So unless you’re a sherpa, it’s best to ascend slowly to give your body more time to adjust to the challenges of a hypoxic environment.
This is an article from I’ve Always Wondered, a series where readers send in questions they’d like an expert to answer. Send your question to email@example.com
In Japan, many people wear face masks – is that to prevent the wearer getting the infection, or is the wearer already infected and protecting those around? Is the mask useful in protecting against viruses or bacteria? – Petrina, Greenwich
Thanks for your question, Petrina. You’re right, in countries like Japan and China, facemask use in the community is widespread – much more so than in Western cultures. People wear them to protect the respiratory tract from pollution and infection, and to prevent the spread of any pathogens they might be carrying.
Whether this works depends on the type of mask.
There are three supposed ways a mask can provide protection: by providing a physical barrier (which prevents splashes and sprays), by filtering the particles (blocking particles of a certain size from entering the respiratory tract), and by fitting around the face to prevent leakage of air around the sides.
Healthcare workers have been using cloth masks (made of cotton or other materials and with ties to secure them at the back) while caring for patients since the late 19th century to protect from various respiratory infections such as diphtheria, scarlet fever, measles, pandemic influenza, pneumonic plague and tuberculosis.
During the mid 20th century, disposable surgical facemasks (similar in look to the cloth masks but made of paper) were developed. Surgical masks were developed to prevent the surgeon from contaminating the wound during surgery, but studies have not proven they help.
These were followed by respirators, which vary in shape and material but are designed to fit around the face and filter particles. Respirators are designed specifically to protect the respiratory tract from inhaled germs. There are many types, which may be reusable or disposable.
People must undergo fit-testing to ensure respirators are correctly fitted, with a good seal around the face. Unlike masks, respirators are subject to certification and regulation, and are proven to protect against respiratory infection.
Surgical masks are unregulated for filtration and do not fit around the face, and the evidence for their use is less convincing. In a community study, families with a sick child who wore such a mask were less likely to get sick if they also wore a mask, but many family members didn’t wear their masks all the time.
In a university setting, students were protected from sick classmates if they wore the mask within 36 hours of their classmate getting sick.
Masks can be used to protect healthy people (such as nurses and doctors) from exposure to infection, but are also used by sick people (such as a TB patient) to prevent spread of infections to others (called “source control”). There is less research on this use than on the use of masks by well people. The efficacy of source control is unknown.
It’s long been thought surgical masks protect from transmission of pathogens, which spread through the air on large, short-range droplets, while respirators protect against much smaller, airborne particles, which may remain suspended in the air for several hours and transmit infection over long distances. So most guidelines recommend a mask for droplet transmitting infections (such as influenza) and a respirator for airborne infections (such as TB and measles).
But we’ve shown respirators protect better than masks even against droplet-spread infections. And the longstanding belief that infections neatly fit into either droplet or airborne transmission is not correct. Respiratory transmission of infections is more complex than this.
To say whether masks work, we have to specify whether we’re talking about a respirator, a surgical mask or a cloth mask.
The respirators are the Rolls Royce option and do protect, and this is a tool for frontline health workers facing epidemics of known and unknown infections. Surgical masks probably also protect but to a lesser extent. But there’s no evidence cloth masks will protect against invading or escaping bugs.
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Ecologists are increasingly using drones to gather data. Scientists have used remotely piloted aircraft to estimate the health of fragile polar mosses, to measure and predict the mass of leopard seals, and even to collect whale snot. Drones have also been labelled as game-changers for wildlife population monitoring.
But once the take-off dust settles, how do we know if drones produce accurate data? Perhaps even more importantly, how do the data compare to those gathered using a traditional ground-based approach?
To answer these questions we created the #EpicDuckChallenge, which involved deploying thousands of plastic replica ducks on an Adelaide beach, and then testing various methods of tallying them up.
As we report today in the journal Methods in Ecology and Evolution, drones do indeed generate accurate wildlife population data – even more accurate, in fact, than those collected the old-fashioned way.
Assessing the accuracy of wildlife count data is hard. We can’t be sure of the true number of animals present in a group of wild animals. So, to overcome this uncertainty, we created life-sized, replica seabird colonies, each with a known number of individuals.
From the optimum vantage and in ideal weather conditions, experienced wildlife spotters independently counted the colonies from the ground using binoculars and telescopes. At the same time, a drone captured photographs of each colony from a range of heights. Citizen scientists then used these images to tally the number of animals they could see.
Counts of birds in drone-derived imagery were better than those made by wildlife observers on the ground. The drone approach was more precise and more accurate – it produced counts that were consistently closer to the true number of individuals.
The difference between the results was not trivial. Drone-derived data were between 43% and 96% more accurate than ground counts. The variation was due to how many pixels represented each bird, which in turn is related to the height that the drone was flown and the resolution of the camera.
This wasn’t a surprise. The experienced ground counters did well, but the drone’s vantage point was superior. Observing photos taken from above meant the citizen scientists did not have to contend with obscured birds that often occur during ground counts. The imagery also benefited the citizen scientists as they could digitally review their counts as many times as they needed. This reduced the likelihood of both missing an individual and counting an individual more than once.
However, even though it proved to be more accurate, making manual digital counts is still tedious and time-consuming. To address this, we developed a computer algorithm in the hope that it could further improve efficiency without diminishing data quality. And it did.
We delineated a proportion of birds in each colony to train the algorithm to recognise how the animal of interest appeared in the imagery. We found that using 10% training data was sufficient to produce a colony count that was comparable to that of a human reviewing the entire scene.
This computerisation can reduce the time needed to process data, providing the opportunity to cut the costs and resources needed to survey wildlife populations. When combined with the efficiencies drones provide for surveying sites that are hard to access on foot, these savings may be considerable.
Using drone monitoring in the field
Our results have important implications for a range of species. We think they are especially relevant to aggregating birds, including seabirds like albatrosses, surface nesting penguins and frigatebirds, as well as colonial nesting waterbirds like pelicans.
Other types of animals that are easily seen from above, including hauled-out seals and dugongs, are highly suited to drone monitoring. The nests or tracks of animals, such as orangutans and turtles, can also be used to infer presence.
Additional experiments will be useful to assess the ability of drones to survey animals that prefer to stay hidden and those within complex habitats. Such assessments are of interest to us, and researchers around the globe, with current investigations focused on wildlife such as arboreal mammals and cetaceans.
The world is rapidly changing, with many negative outcomes for wildlife. Technology like drones can help scientists and managers gather data fast enough to enable timely assessment of the implications of these changes.
When monitoring wildlife, increasing the accuracy and precision of animal surveys gives us more confidence in our population estimates. This provides a stronger evidence base on which to make management decisions or policy changes. For species and ecosystems threatened with extinction or irreparable damage, such speedy action could be a literal lifeline.
Peat means different things to different people. To many Irish people, it means fuel. To the Scottish, it adds a smoky flavour to their whisky. Indonesia’s peatlands, meanwhile, are widely known as the home of orangutans, the palm oil industry, and the persistent fires that cause the infamous Southeast Asian haze.
Indonesians, and other people with ties to these peatlands, have a range of perspectives on the value of peat – both commercial and otherwise.
Here we explore them through the eyes of four fictitious but representative characters.
Peatland is my land. As migrants from Java, my family now have our own house and our own crops. In some years there have been terrible fires, with smoke so thick we can’t even see the end of our street, and all of our food crops burn. But in other years, the rice and corn grow well, my family eat fish every day, my wife smiles, and our children grow tall.
In Java we had no land of our own, and I worked as a farm labourer. Here in Sumatra we have our own peatland. It is different from Javanese soil but we work hard to tend our crops, watering them in the dry season and protecting them from fire.
A big palm oil company has trained me and 50 other men from our village in firefighting. We have uniforms and water-holding backpacks, and I have learned about when the fire will come. They are helping us to protect our palms, and their own palms, of course. My palms are still young, but in a few years I will sell the palm oil fruit to the company, and then my boys can go to high school in town – as long as the palms don’t burn, God willing.
Floods are a harder problem. How can I protect my land? The government dug canals to drain the peatland before we came, but they are not big enough to hold all the water that comes from the heavens and the floods come more and more often.
The official in Jakarta
Peatland is our burden. Indonesia has fertile land, rich oceans… and then there are the peatlands. It is always either too wet to use, or so dry that it burns.
Other Southeast Asian governments want us to end the fires and haze single-handed, but Indonesia isn’t the only one to blame; peatland fires are a regional problem.
We are caught between domestic and international pressures. Develop our peatlands to lift our people out of poverty, or preserve them for orangutans and carbon storage. Of course, the Indonesian people are my priority.
When I studied agriculture at university in Brisbane in the 1990s, my classmates were a little fuzzy about where Indonesia is, let alone what happens here. Now, when our ministry visits Canberra, I feel sad to see “Palm Oil Free” displayed prominently on supermarket products. Westerners don’t understand that not all palm oil is grown on peatlands, that it is a healthy oil and a highly efficient crop perfectly suited to tropical conditions.
Our ministry is working hard to ensure that Indonesia develops our peatlands sustainably, restoring and rewetting degraded areas and working with the local people to find economic uses for wet peat. My son wants to follow in my footsteps and work on peatlands too, and has applied to study sustainable development at university in Singapore.
So while peatlands are currently a source of national embarrassment, many minds are focused on transforming them into the goose that lays the golden egg for Indonesia.
Peatland is good, profitable land. For too long we have considered it wasteland – too wet, too far away. But technology from peat-rich countries like Finland and Canada is helping us to use tropical peatlands for people.
My pulp and paper company has half of its plantations on peatlands, which produce more than a third of our pulpwood. My silviculture (forest management) team works closely with my environmental manager and PR team to ensure that our plantations are grown according to best practice, and that our shareholders and clients know it.
The community benefits in the regions around our plantations are easy to see. The village that my parents came from has electricity now, and big modern houses have replaced the old wooden ones. We have paved the road and our taxes support the government’s new health centre and primary school.
The Indonesian government doesn’t want any more fires, and neither do we – we don’t want our plantations to burn! But the new regulations that require rewetting the peat are a big challenge for us. What will grow in wet peatland?
I lie awake at night worrying about my company’s future. What species can we diversify into? Should we move away from pulp and into bioenergy? Are we putting enough money into R&D? Should I spend more on lobbying? My son is studying for an MBA in the United States, but will there still be a profitable business for him to join when he graduates?
The orangutan carer
We rescued Fi Fi from an area that used to be peatland forest but has been cleared for palm plantations. With no food and nowhere to make a nest, Fi Fi and her mother gradually got weaker and weaker, until workers at the plantation noticed and called us. The mother died before we could help her.
That was nine months ago, and I’ve been caring for Fi Fi around the clock since then in a babysitting team with my friend Nurmala. Fi Fi loves cuddles, milk and fruit, just like my children did at her age.
It is a good job, and we have a great team. Everyone is passionate about protecting the orangutans and the forest. We would like to be able to release Fi Fi once she has learned all her forest skills. Orangutans can look after themselves from about seven years old. But they need a lot of space.
Peatland fires, logging and oil palm planting destroy more forest every year, so places for Fi Fi to be released are hard to find. My brothers and sisters are all happy to stay living near our family home, and when I’m not here looking after Fi Fi, I always have my nieces and nephews on my knee.
I love to have them close, but when the dry season fires come and the haze is so thick I can’t even see my brother’s house across the street, I sometimes wish they had flown a bit further from the nest. Last year we were in and out of the health clinic for a month with my niece’s breathing problems.
I spend all my time caring for precious little ones – both human and orangutan – but the issues themselves are too big for me to fight.
People are central to the problem of tropical peatland fires. In their natural state, tropical peat swamp forests are too wet to burn. Drainage, installed by people for forestry, palm oil, roads, mining and other development, lowers the water table and dries out the peat. Many peat fires smoulder for months, from the start of dry season in July until the monsoon returns in November.
These fires have a wide range of negative effects: on local health, regional economies and the global carbon cycle. Indonesia’s president, Joko Widodo, has created a new Peatland Restoration Agency, and announced policies to restrict burning and draining of the peat beyond a maximum water table depth of 40cm below the surface. However, action is still disjointed and ministries are, at times, working at cross purposes.
The truth is that only when enough people value wet peatlands will the fires be prevented. Wet peatlands are great for orangutans and the global climate, but how about local smallholders, government officials and business investors? Saving peatlands will require creating value for these people too.
What crops can be profitably grown with a water table high enough to prevent burning? How can smallholders tap into a carbon trading market? Rather than cutting trees to send their children to school, can they earn more money by protecting the carbon stored in peat? Can villagers be empowered to make a better living from ecotourism than illegal logging?
Humans are integral to Indonesia’s tropical peatlands. And they must be at the centre of the solutions too. Otherwise the fires will keep burning – and none of the four people whose stories we’ve heard want that.
If we can convince people that climate change is real and important, then surely they will act: this intuitive idea underlies many efforts to communicate climate change to the public.
Initially it was very successful in increasing public awareness and support, but anyone aware of the protracted climate change “debate” can see that people who are still unconvinced are now very unlikely to be swayed.
In research published in Nature Climate Change today, my colleagues and I show that people will support action on climate change if it helps to create a better society.
To reinvigorate people’s support for climate change action, we may need to look at options other than just convincing people that climate change is real. Rather than trying to persuade people that climate change is more important than their other concerns and goals, perhaps we should start with those concerns and goals and show how they can be addressed through tackling climate change.
For example, if action on climate change reduces pollution or stimulates economic development, people who value clean air or economic growth might support climate change action, even if they are unconvinced or unconcerned about climate change itself. These broader positive effects of climate change action are often called “co-benefits”.
But could such co-benefits motivate people to act? If so, might different co-benefits matter more to people in different countries? These questions have been the focus of our large international research project examining the views of more than 6,000 people from 24 countries.
Through this research, we aimed to identify the key co-benefits that motivate behaviour around the world to help create more effective ways of designing and communicating climate change initiatives.
Fixing climate change, fixing other problems
We asked people whether the social conditions in their country would become better or worse as a result of climate change mitigation, including a wide range of potential co-benefits.
We found that people grouped these co-benefits into larger clusters relating to promoting development (such as economic development, scientific progress) and reducing dysfunction (such as poverty, crime, pollution, disease).
As social psychologists, we were also interested in how addressing climate change could influence people’s character. We asked people how taking climate change action might result in people in society becoming more (or less) caring and moral (benevolence), and capable and competent (competence).
We related these four overarching co-benefits to people’s motivations to engage in behaviours to address climate change. These include public behaviours (such as green voting and campaigning), private behaviours (such as reducing household energy use) and financial behaviours (donating to an environmental organisation).
Around the world, two types of co-benefits were strongly related to motivations to act in public, at home, or in providing financial support.
People were motivated to act on climate change when they thought it would lead to scientific and economic advances (development), and when it would help create a society where people cared more for each other (benevolence).
Yet there was an important difference between who favoured benevolence and development. Making society more caring was a strong motivator for action across the globe, whereas promoting development varied in its effects across countries.
For example, development was a strong motivator in France and Russia, but only a weak motivator in Japan and Mexico. However, we could not identify a systematic reason for this cross-country difference.
Surprisingly, reducing pollution, poverty and disease was the weakest motivator of climate change action, despite issues like pollution and poor health being commonly invoked as co-benefits of addressing climate change, such as the US climate action plan.
Critically, if people thought acting on climate change would improve society in these ways, it didn’t matter if they believed it was happening or not, or whether it was important. And it didn’t matter what political ideology they held.
This shows how these co-benefits can cut across ideological and political divides that are stalling climate change discussions.
Climate policy with something for everyone
The findings can help communicate climate change to the public in more convincing ways, but the real key is to ensure that climate change initiatives can achieve these development and benevolence co-benefits.
While the economic opportunities of addressing climate change already receive public discussion, it may be less obvious how climate change policies could help create communities where people care more for each other.
“Top-down” policies such as a carbon tax or emissions trading aren’t traditionally the stuff that helps build communities. However, policies that support “bottom-up” initiatives have this potential, such as engaging local communities in climate change activities that build friendships and strengthen networks.
These findings should strengthen the hands of those arguing for bottom-up approaches at the UN Climate Change Conference in Paris in December. If climate change policies and initiatives can produce these co-benefits for the economy and the community, people around the world will support action.
Paul will be on hand for an Author Q&A between 12:30 and 1:30pm AEST on Tuesday, September 29, 2015. Post your questions in the comments section below.
If you’ve always wanted to visit China, this … this might not be the best time. Thanks to climate change, massive numbers of Asian giant hornets (which are the size of your thumb) have been rolling through Shaanxi Province, eating honeybees, and stinging humans to death. And they could be coming to your area next.